Micro-led displays

ABSTRACT

A micro-light emitting diode (LED) display panel and a method of forming the display panel, the micro-LED display panel having a monolithically grown micro-structure including a first color micro-LED that is a first color nanowire LED, and a second color micro-LED that is a second color nanowire LED.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a Divisional Application of U.S. patentapplication Ser. No. 15/283,180, by Khaled Ahmed et al., titled“MICRO-LED DISPLAYS,” filed Sep. 30, 2016, and which is incorporatedherein by reference.

TECHNICAL FIELD

The present disclosure relates to micro-LED displays.

BACKGROUND

Displays having microscopic light-emitting diodes (LEDs) are known asmicro-LED, mLED, and μLED. As the name implies, micro-LED displays havearrays of micro-LEDs forming the individual pixel elements.

A pixel may be a minute area of illumination on a display screen, one ofmany from which an image is composed. In other words, pixels may besmall discrete elements that together constitute an image as on adisplay. These primarily square or rectangular-shaped units may be thesmallest item of information in an image. Pixels are normally arrangedin a 2-dimensional grid, and are represented using dots, squares, orrectangles. Pixels may be the basic building blocks of a display ordigital image and with geometric coordinates.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatical representation of a micro-LED display panelmanufacture.

FIG. 2 is a diagrammatical representation of a micro-LED display panelmanufacture.

FIG. 3 is a graph of energy gap of indium GaN versus indium content ofthe indium GaN.

FIG. 4 is a graph of internal quantum efficiency of indium GaN versusindium content of the indium GaN.

FIG. 5 is a block flow diagram of a method of forming a micro-LEDdisplay panel in accordance with embodiments of the present techniques.

FIG. 6 is a diagram of a micro-structure having two micro-LEDs grownmonolithically in accordance with embodiments of the present techniques.

FIG. 7 is an electronic device having a display in accordance withembodiments of the present techniques.

The same numbers are used throughout the disclosure and the figures toreference like components and features. Numbers in the 100 series referto features originally found in FIG. 1; numbers in the 200 series referto features originally found in FIG. 2; and so on.

DESCRIPTION OF THE EMBODIMENTS

The present techniques relate to micro-LED displays and to manufactureof micro-LED displays to give lower cost and lower power consumption. Areduction in power consumption may be an objective of electronicsdesign. Indeed, decreasing electrical consumption may be beneficial formobile devices due to the generally limited power storage of mobiledevices. Moreover, displays may consume a considerable portion (30%-70%)of the total power consumption of a mobile device such as withsmartphones, smartwatches, and tablets.

FIG. 1 is a diagrammatical representation of a micro-LED display panelmanufacture 100. A representation of micro-LED transfers generally fromwafer 102 to glass backplane 104 is depicted in FIG. 1. To make activematrix micro-LED display panels, GaN-based micro-LEDs may be fabricatedon wafers 102 (e.g., silicon or sapphire). The micro-LEDs may then betransferred from the wafers 102 to thin-film transistor (TFT) backplanes104 to make pixels that form the active matrix micro-LED display panel.For a given pixel, the transfer process may be executed multiple times.

As will be discussed in greater detail below, some embodiments mayreduce the number of separate transfers per pixel. This may also meanthat the transfer time per pixel is reduced. Also, in some examples, thereduction in number of transfers may not result in an increase orsignificant increase of defects in the display panel.

FIG. 2 is a diagrammatical representation of a micro-LED display panelmanufacture 200. A stamp 202 collects or “picks-up” micro-structuresfrom the source substrate 204 which may be a native substrate with“printable” or “transferrable” micro-structures. In other words, thestructures are transferred from the source substrate 204 onto the stamp202. The micro-structures may be temporarily coupled (adhered orattached) to the stamp 202, for example, by Van der Waals forces. Amicro-structure may be a micro-LED having multiple nanowires. On theother hand, as discussed below, a micro-structure may be two micro-LEDsgrown monolithically (see, e.g., FIG. 7) and each with a plurality ofnanowires.

The stamp 202 places, disperses, or prints the micro-structures onto areceiving device substrate 206. Indeed, a transfer places the collectedstructures onto the device substrate 206 leaving a partially-depletedsource substrate 208 having remaining micro-structures not collected andtransferred. The transfer process may be repeated and continue untilmost or all of the micro-structures on the source substrate 204 aretransferred to the device substrate 206. In general, in micro-transfer,a stamp 202 may be utilized to transfer microscale devices from theirnative substrates (e.g., 204) onto non-native substrates (e.g., 206).

The production cost of micro-LED displays may be sensitive to thetransfer tact time of micro-LEDs from source wafers 102 to host-glassTFT backplanes 104 (see FIG. 1), including for large-size displays suchas with tablets or notebooks. Moreover, defect density after suchtransfer should generally be less than 1 part per million (ppm) for somemicro-LED panels. Some embodiments may combine some of these transfers(and therefore reduce the number of transfers without adverselyaffecting quality of the micro-LED display panel) by growingmonolithically two types of micro-LEDs on the same source wafer (e.g.,growing monolithically both blue and green micro-LEDs on the same sourcewafer).

Micro-LEDs may be made from nanowires with an inner core of galliumnitride (GaN) and an outer layer of indium-gallium-nitride (InGaN).Increasing the diameter of the nanowires may increase the indium contentof the nanowires and the micro-LED, thereby affecting the color emissionof the micro-LED. The indium composition in InGaN to emit blue to redmay be over a relatively large range from about 20% (e.g., +/−3%) toabout 41% (e.g., +/−3%). The term “monolithic” may be seen as formed orintegrated as a single unit.

For example, the present techniques may monolithically grow twomicro-LEDs (one for a first color and one for a second color) with arelatively narrow range of indium compositions on the same wafer. Forinstance, a blue (B) nanowire LED and green (G) nanowire LED may bemonolithically grown on a wafer to give BG nanowire LEDs, which is amicro-structure having a B micro-LED and a G micro-LED. This BG nanowiremicrostructure has a first diameter for B nanowires (B micro-LED) and asecond diameter for G nanowires (G micro-LED), for example, where Gnanowires have less diameter than that of B nanowires. The diameter forB may give about 20% indium content, and the diameter for G may giveabout 31% indium content. Another example grows monolithically a green(G) nanowire LED and a red (R) nanowire LED to give GR nanowire LEDswith one diameter giving about 31% indium content for G and anotherdiameter giving about 41% indium content for R.

FIG. 3 is a graph 300 of energy gap 302 of InGaN in electronvolts (eV)versus the mass fraction of indium content 304 in the InGaN. Thus, thecurve 306 is energy gap (eV) of InGaN over mass fraction range of indiumcontent from 0 to 1. An indium content 304 of zero is GaN with noindium. An indium content 304 of 1 is indium with no GaN. As depicted,the circle 308 represents blue (B) at about 21% indium content. Thecircle 310 represents green (G) at about 31% indium content. Circle 312represents yellow (Y) at about 37% indium content. Lastly, the circle314 represents red (R) at about 41% indium content.

Again, some embodiments monolithically grow two-color LEDs withrelatively narrow range of indium compositions on the same wafer. Inother words, two different color micro-LEDs are grown monolithically atthe same time on the same wafer. For instance, as mentioned, by usingnanowires, the emission color may be changed from blue to red withincreasing nanowire diameter. Some examples are to monolithically growblue and green nanowire LEDs (for the pixel), monolithically grow greenand red nanowire LEDs (for the pixel), and transfer separately a Bmicro-LED, the B and G micro-LEDs (monolithically grown), G and Rmicro-LEDs (monolithically grown), and a R micro-LED from wafers 102 todisplay backplanes 104 (see FIG. 1). Benefits of some embodiments mayinclude lower cost and reduced defects of the micro-LED display panels,and generally increased power efficacy of two colors with close indiumcomposition in the InGaN materials.

Thus, monolithic productions of blue and green nanowire LEDs areperformed simultaneously on the same wafer by using different nanowirecore diameters to change the indium composition in the InGaN activeemitting junction. Such may occur during a latter portion of the growth.In other words, the change in diameter to impact indium content may beimplemented to the InGaN layer which may occur after the growth of theGaN core.

Since the indium composition for blue and green are about 20% and about31%, respectively, the same metalorganic vapor phase epitaxy (MOVPE)process parameters for each color may be satisfactory to produceadequate power efficacy for both blue and green LEDs at the same time.Likewise, because the indium composition for green and red are about 31%and about 41%, respectively, the same MOVPE process parameters for eachcolor may be satisfactory to produce adequate power efficacy for bothgreen and red LEDs at the same time.

Similarly, monolithic productions of green and yellow color LEDs may beperformed simultaneously on the same wafer by using different nanowirecore diameters to change the Indium composition in the InGaN activeemitting junction later on. Since the Indium composition for green andyellow are about 31% and about 37%, respectively, the same MOVPE processparameters may be satisfactory to produce adequate power efficacy forboth green and yellow LEDs at the same time. Also, monolithicproductions of yellow and red color LEDs may be performed simultaneouslyon the same wafer by using different nanowire core diameters to changethe Indium composition in the InGaN active emitting junction. The sameMOVPE process parameters for each color may be satisfactory to produceadequate power efficacy for both yellow and red LEDs at the same timebecause the Indium compositions for green and yellow are close at about37% and about 41%, respectively. Again, as indicated, the aforementionedvarious growths to change diameter may occur during a latter portion ofthe growth, affecting the InGaN layer after growth of the GaN core. Ingeneral, the above techniques may provide redundancy, as well as meetingcost and power efficacy targets.

FIG. 4 is a graph 400 for InGaN/GaN quantum well (QW) LEDs and depictinginternal quantum efficiency (IQE) 402 of InGaN versus the mass fractionof indium content 404 in the InGaN. Thus, the curve 406 is IQE of InGaNover the mass fraction range of indium content from 0 to 1. An indiumcontent 404 of zero is GaN with no indium. An indium content 404 of 1 isindium with no GaN. Thus, the curve 406 is energy gap (eV) of InGaN overmass fraction range of indium content from 0 to 1. An indium content 300of zero is GaN with no indium. An indium content 304 of 1 is indium withno GaN. As depicted, the circle 408 represents blue (B) at about 21%indium content. The circle 410 represents green (G) at about 31% indiumcontent. Circle 412 represents yellow (Y) at about 37% indium content.Lastly, the circle 414 represents red (R) at about 41% indium content.As indicated above, the percentage indium for each color may vary withina tolerance such as +/−3%.

FIG. 5 is a method 500 of forming a micro-LED display panel to havepixels which may be labeled as blue-green-red (BGR) pixels or RGBpixels, and so on. As discussed below, micro-LEDs as nanowire LEDs maybe grown or formed on wafers, and then the micro-LEDs subsequentlytransferred from the wafers to a backplane for the micro-LED displaypanel. Moreover, each micro-LED generally has multiple nanowires. Thediameter of each nanowire may be function of the desired color for thenanowire to emit. In other words, different diameters may have differentindium content of InGaN in the nanowires.

At block 502, the method includes forming or growing monolithically bothblue (B) nanowire LEDs and green (G) nanowire LEDs on a source wafer.The forming or growing includes growing indium gallium nitride (InGaN).Further, the growing monolithically may include forming nanowire LEDs,where some of the micro-LEDs have a first nanowire diameter such thatthey form blue micro-LEDs and other micro-LEDs have a second diametergreater than the first diameter such that they form green micro-LEDs. Inother words, the first diameter (smaller diameter for B) gives a lowerindium content, and the second diameter (larger diameter for G) gives agreater indium content.

At block 504, the method includes growing monolithically both green (G)nanowire LEDs and red (R) nanowire LEDs on a source wafer. The methodmay include growing other types of nanowire LEDs. For example, themethod may include monolithically growing green (G) nanowire LEDs andyellow (Y) nanowire LEDs on a source wafer, monolithically growingyellow (Y) nanowire LEDs and red (R) nanowire LEDs on a source wafer,and the like. Again, monolithically growing may mean growingsimultaneously on the same source wafer. Also, the method may includegrowing nanowire LEDs not monolithically grown with another colornanowire LED. For example, the method may include growing a blue (B)nanowire LED on a source wafer to give a B nanowire LED on the sourcewafer, growing a red (R) nanowire LED on a source wafer to give a Rnanowire LED on the source wafer, and so on.

At block 506, the nanowire LEDs are transferred from the source wafer(s)to a backplane to form the micro-LED display panel with the backplane.Indeed, the method includes transferring a micro-structure having a bluenanowire LED and a green nanowire LED monolithically grown from a singlesource wafer to the backplane for a given pixel. The method may includetransferring another micro-structure having a green nanowire LED and ared nanowire LED from a single source wafer to the backplane for thegiven pixel. The method may include transferring the blue nanowire LED(not monolithically grown) from its source wafer to the backplane forthe given pixel, transferring the red nanowire LED (not monolithicallygrown) from its source wafer to the backplane, and the like. Other colorintegrated combinations and types of nanowire micro-LEDs formed may betransferred. In one example, the number of transfers for the pixel isnot greater than four transfers: a transfer of a blue nanowire LED, atransfer of the blue-green nanowire LEDs micro-structure, a transfer ofthe green-red nanowire LEDs micro-structure, and a transfer of a rednanowire LED. Lastly, the method 500 may include forming the micro-LEDdisplay with the backplane, and forming or installing the micro-LEDdisplay panel in a display or electronic device.

With respect to FIG. 5, the method 500 of forming a micro-LED displaypanel at block 502 may more generally include growing monolithically(e.g., growing InGaN) a first color nanowire LED and a second colornanowire LED on a wafer to give a micro-structure having a first colormicro-LED and a second color micro-LED, the second color different thanthe first color. As depicted in block 502, the colors may be first coloras blue and the second color a green. However, other options are thefirst color as green and the second color as red, or the first color asgreen and the second color as yellow, or the first color as yellow andthe second color as red, and so on. For the micro-structure, the methodmay include monolithically growing a first plurality of nanowires to afirst diameter for the first color nanowire LED and a second pluralityof nanowires to a second diameter for the second color nanowire LED, thesecond diameter larger than the first diameter.

At block 504, the method may more generally include growingmonolithically a second color nanowire LED and a third color nanowireLED on another wafer to give a second micro-structure having a secondcolor micro-LED and a third color micro-LED. As depicted in block 504,the second color may be green and the third color red. However, othercolor options are applicable.

At block 506, the method includes transferring this micro-structure(formed in block 502) from the wafer to a backplane for a pixel of themicro-LED display, and transferring the second micro-structure (formedin block 504) from the another wafer to the backplane for the pixel. Inone example, the first color is blue, the second color is green, and thethird color is red. Moreover, in some examples, the action in block 506of performing transfers to the backplane for the pixel may includeperforming four separate transfers including the transferring of thefirst micro-structure from the wafer to the backplane, the transferringof the second micro-structure from the another wafer to the backplane,transferring a blue micro-LED comprising a blue nanowire LED to thebackplane from a third wafer, and transferring a red micro-LEDcomprising a red nanowire LED to the backplane from a fourth wafer.Optionally, no more transfers than these four separate transfers areperformed for the pixel.

As mentioned, nanowires are very small, such as, for example, about 2micrometers height or length and about 10-500 nanometers in diameter.Nanowires for LEDs may be made of an inner core of gallium nitride (GaN)and a layer of indium-gallium-nitride (InGaN) on the outside, both ofwhich are semiconducting materials.

In some examples, the nanowire architecture in contrast to planar LEDsmay involve the growth of n-type GaN core followed by sequential “radialgrowth” of intrinsic InGaN and p-type GaN shells. In accordance with thepresent disclosure, processes for making nanowire micro-LEDs may involvea buffer epitaxial (EPI) wafer, nanoimprint lithography (NIL), nanowireEPI wafer, multiple quantum well (MQW) EPI, micro LED patterning,contact, and the like. The techniques may be applied for small micro-LEDscreens (e.g., wearable watches, etc.) and devices with larger micro-LEDscreens (e.g., notebooks, tablets, etc.).

FIG. 6 is an example micro-structure 600 having two micro-LEDs 602 and604 grown monolithically at the same time on the same wafer 606.Therefore, the two micro-LEDs can be transferred together as amicro-structure 600 in a single transfer from the wafer 606 to areceiving or device substrate such as a backplane of a micro-LED displaypanel. Further, each micro-LED 602 and 604 is depicted as having fournanowires for clarity. The micro-LEDs 602 and 604 may each have morethan four nanowires, and may have many more than four nanowires.Moreover, the first micro-LED 602 has nanowires with a first diameter soto emit a first color. The second micro-LED 604 has nanowires with asecond diameter in order to emit a second color which is different thanthe first color. As discussed, the color emission may be a function ofthe indium content which may be affected by the nanowire diameter.Indeed, the diameter of a nanowire (having an InGaN layer or shell) canbe increased during growth to increase the indium content and,therefore, change the color of the micro-LED 602 or 604. In someexamples, the micro-LED 602 is a blue (B) micro-LED and the micro-LED604 is a green (G) micro-LED. In other examples, the micro-LED 602 is agreen (G) micro-LED and the micro-LED 604 is a red (R) micro-LED. In yetother examples, the micro-LED 602 is a yellow (Y) micro-LED and themicro-LED 604 is a red (R) micro-LED. In general, the micro-LED 602 is afirst color micro-LED and the micro-LED 604 is a second color micro-LED,the second color different than the first color.

In the illustrated example, a nanowire has an inner shell 608 of InGaNand an outer shell 610 of p-GaN which may be GaN doped with a p-typedopant such as acceptor impurities (e.g., boron). The core 612 of thenanowire is n-GaN which may be GaN doped with a n-type dopant such asdonor impurities (e.g., phosphorus). The shells 608 and 610 may be grownor formed on a mask 616 such as a silicon nitride (Si3N4) mask. The core612 may be grown or formed on a n-GaN layer 614 and a buffer stack 618such as aluminum gallium nitride (AlGaN), Si3N4, or other materials.Other configurations are applicable. Lastly, the multiple nanowires of amicro-LED 602 or 604 may share an electrode 620 (e.g., a transparentelectrode). Thus, in the illustrated embodiment, multiple nanowiresshare the same electrode 620 to form a single micro-LED 602 or 604

Again, two micro-LEDs 602 and 604 (one for one color and the other foranother color) may be transferred together from the source wafer 606because the two different-color micro-LEDs were grown monolithically onthe same wafer 606.

FIG. 7 is an electronic device 700 having a display or display panel 702with a micro-structure 704 (e.g., micro-structure 600 of FIG. 6) havingtwo micro-LEDs that were grown monolithically at the same time on thesame source wafer. The first micro-LED has nanowires with a firstdiameter (e.g., a first indium content) so to emit a first color. Thesecond micro-LED has nanowires with a second diameter (e.g., a secondindium content) so to emit second color which is different than thefirst color. Again, the nanowires in the micro-structure 704 for bothmicro-LEDs are grown together simultaneously or monolithically on thesame wafer, but with the diameter of nanowires being different permicro-LED. In some examples for the micro-structure 704, the firstmicro-LED is a blue micro-LED and the second micro-LED is a greenmicro-LED. In other examples for the micro-structure 704, the firstmicro-LED is a green micro-LED and the second micro-LED is a redmicro-LED. In yet other examples for the micro-structure 704, the firstmicro-LED is a yellow micro-LED and the second micro-LED is a redmicro-LED. Other color examples are applicable.

The display may also have glass layers and other layers, circuitry, andso forth. The display panel 702 may be a micro-LED display panel. Asshould be apparent, only one microstructure 704 is depicted for clarity,though a display panel 702 will have an array or arrays ofmicrostructures comprising nanowire LEDs.

The electronic device 700 may be a mobile device such as smartphone,tablet, notebook, smartwatch, and so forth. The electronic device 700may be a computing device, stand-alone display, television, displaymonitor, vehicle computer display, the like. Indeed, the electronicdevice 700 may generally be any electronic device having a display ordisplay panel.

The electronic device 700 may include a processor 706 (e.g., a centralprocessing unit or CPU) and memory 708. The memory 708 may includevolatile memory and nonvolatile memory. The processor 706 or othercontroller, along with executable code store in the memory 708, mayprovide for touchscreen control of the display and well as for otherfeatures and actions of the electronic device 700.

In addition, the electronic device 700 may include a battery 710 thatpowers the electronic device including the display panel 702. The device700 may also include a network interface 712 to provide for wired orwireless coupling of the electronic to a network or the internet.Wireless protocols may include Wi-Fi (e.g., via an access point or AP),Wireless Direct®, Bluetooth®, and the like. Lastly, as is apparent, theelectronic device 700 may include additional components includingcircuitry and other components.

The micro-LED display panel 702 of the electronic device 700 may have amonolithically grown micro-structure including a first color micro-LEDthat is a first plurality of nanowires and a second color micro-LED thatis a second plurality of nanowires, the second color different than thefirst color. The first plurality of nanowires has nanowires with a firstdiameter, and the second plurality of nanowires has nanowires with asecond diameter different than the first diameter. For example, if thefirst color is blue and the second color is green, the second diameterwould be larger than the first diameter. Further, the micro-LED displaypanel 702 may have a monolithically-grown second micro-structureincluding a second color micro-LED that is a third plurality ofnanowires and a third color micro-LED that is a fourth plurality ofnanowires. In some examples, the first color is blue, the second coloris green, and the third color is red.

An embodiment may include a micro-LED display panel having a blue-green(BG) micro-structure including a blue (B) micro-LED (having a firstplurality of nanowires) and a green (G) micro-LED (having a secondplurality of nanowires) grown monolithically for a pixel of the displaypanel. Further, the micro-LED display panel may include a green-red (GR)micro-structure having a green (G) micro-LED (having a third pluralityof nanowires) and a red (R) micro-LED (having a fourth plurality ofnanowires) grown monolithically for the same or different pixel. Themicro-LED display panel may include a second blue (B) micro-LED (havinga fifth plurality of nanowires) and a second red (R) micro-LED (having asixth plurality of nanowires) for the same or different pixel. Indeed, asingle pixel of the micro-LED display panel may include the BGmicro-structure, the GR micro-structure, the second B micro-LED, and thesecond R micro-LED.

Another embodiment is an electronic device with a micro-LED displaypanel having a pixel which may be labeled as a BGR or RGB pixel, whereinthe pixel includes a blue-green LED micro-structure having a bluenanowire LED and a green nanowire LED grown monolithically. The pixelmay include a green-red LEDs micro-structure having a green nanowire LEDand a red nanowire LED grown monolithically. Further, the pixel mayinclude a second blue nanowire LED and a second red nanowire LED.

Yet another embodiment (see, e.g., FIG. 5) includes a method of forminga micro-LED display panel having pixels which may be labeled as BGR orRGB pixels. The method may include forming the micro-LED display panelwith a backplane. The method may include installing the micro-LEDdisplay panel in a display.

To form LEDs on a source wafer, the method may include growingmonolithically a blue nanowire LED and a green nanowire LED on the samewafer to give a micro-structure having a blue micro-LED and a greenmicro-LED. In other words, a first plurality of nanowires may be grownto a first diameter for blue nanowire LED and a second plurality ofnanowires grown to a second diameter for the green nanowire LED, thesecond diameter larger than the first diameter. The method includestransferring the micro-structure from the wafer to a backplane for apixel which may be labeled as a BGR or RGB pixel, wherein themicro-structure to provide emission colors of blue (B) and green (G).The method may include growing monolithically a green nanowire LED and ared nanowire LED on a wafer to give a green-red micro-structure having agreen micro-LED and a red micro-LED, and transferring the green-redmicro-structure to the backplane for the pixel. Further, the method mayinclude growing a red nanowire LED as a red micro-LED and transferringthe red micro-LED to the backplane for the pixel. The method may includegrowing a blue nanowire LED as a blue micro-LED and transferring theblue micro-LED to the backplane for the pixel. The aforementionedgrowing of nanowires and micro-LEDS may include growing indium galliumnitride (InGaN).

In addition, the method may include performing four separate transfersto the backplane for the pixel, including transferring the blue (B)nanowire LED to the backplane, transferring the BG micro-structure tothe backplane, transferring the GR micro-structure to the backplane, andtransferring the red (R) nanowire LED to the backplane. In particularexample, no more transfers than these four separate transfers areperformed for the pixel. However, the method may include growingmonolithically a green nanowire LED and a yellow nanowire LED to give amicro-structure having a green micro-LED and a yellow micro-LED, andtransferring that micro-structure to the backplane. Further, the methodmay include growing monolithically a yellow nanowire LED and a rednanowire LED to give a another micro-structure, and transferring thatmicrostructure to the backplane.

Yet another embodiment (see, e.g., FIG. 5) is a method of manufacturinga micro-LED display panel having pixels, including: growingmonolithically a blue (B) nanowire LED and a green (G) nanowire LED togive a BG micro-structure having a B micro-LED and a G micro-LED;growing monolithically a green (G) nanowire LED and a red (R) nanowireLED to give a GR micro-structure having a G micro-LED and a R micro-LED;growing a blue (B) nanowire LED comprising a B micro-LED; growing a red(R) nanowire LED comprising a R micro-LED; and performing four separatetransfers to a backplane substrate for a pixel of the micro-LED displaypanel, including a first transfer of the B micro-LED, a second transferof a BG micro-structure, a third transfer of the GR micro-structure, anda fourth transfer of the R micro-LED. In certain examples, no moretransfers than the four separate transfers are performed for the pixel.The method may include forming the micro-LED display panel with thebackplane substrate. Lastly, the method may include installing themicro-LED display panel in a display of an electronic device such as amobile device.

In the description and claims, the terms “coupled” and “connected”,along with their derivatives, may be used. It should be understood thatthese terms are not intended as synonyms for each other. Rather, inparticular embodiments, “connected” may be used to indicate that two ormore elements are in direct physical or electrical contact with eachother. “Coupled” may mean that two or more elements are in directphysical or electrical contact. However, “coupled” may also mean thattwo or more elements are not in direct contact with each other, but yetstill co-operate or interact with each other.

Some embodiments may be implemented in one or a combination of hardware,firmware, and software. Some embodiments may also be implemented asinstructions stored on a machine-readable medium, which may be read andexecuted by a computing platform to perform the operations describedherein. A machine-readable medium may include any mechanism for storingor transmitting information in a form readable by a machine, e.g., acomputer. For example, a machine-readable medium may include read onlymemory (ROM); random access memory (RAM); magnetic disk storage media;optical storage media; flash memory devices; or electrical, optical,acoustical or other form of propagated signals, e.g., carrier waves,infrared signals, digital signals, or the interfaces that transmit orreceive signals, among others.

An embodiment is an implementation or example. Reference in thespecification to “an embodiment”, “one embodiment”, “some embodiments”,“various embodiments”, or “other embodiments” means that a particularfeature, structure, or characteristic described in connection with theembodiments is included in at least some embodiments, but notnecessarily all embodiments, of the present techniques. The variousappearances of “an embodiment”, “one embodiment”, or “some embodiments”are not necessarily all referring to the same embodiments. Elements oraspects from an embodiment can be combined with elements or aspects ofanother embodiment.

Not all components, features, structures, characteristics, etc.described and illustrated herein need be included in a particularembodiment or embodiments. If the specification states a component,feature, structure, or characteristic “may”, “might”, “can”, or “could”be included, for example, that particular component, feature, structure,or characteristic is not required to be included. If the specificationor claim refers to “a” or “an” element, that does not mean there is onlyone of the element. If the specification or claims refer to “anadditional” element, that does not preclude there being more than one ofthe additional element.

It is to be noted that, although some embodiments have been described inreference to particular implementations, other implementations arepossible according to some embodiments. Additionally, the arrangement ororder of circuit elements or other features illustrated in the drawingsor described herein need not be arranged in the particular wayillustrated and described. Many other arrangements are possibleaccording to some embodiments.

In each system shown in a figure, the elements in some cases may eachhave a same reference number or a different reference number to suggestthat the elements represented could be different or similar. However, anelement may be flexible enough to have different implementations andwork with some or all of the systems shown or described herein. Thevarious elements shown in the figures may be the same or different.Which one is referred to as a first element and which is called a secondelement is arbitrary.

Examples are given. Example 1 is a method of forming a micro-lightemitting diode (LED) display panel. The method includes growingmonolithically a first color nanowire LED and a second color nanowireLED on a wafer to give a micro-structure having a first color micro-LEDand a second color micro-LED, the second color different than the firstcolor; and transferring the micro-structure from the wafer to abackplane for a pixel of the micro-LED display, wherein themicro-structure to provide emission colors of the first color and thesecond color.

Example 2 includes the method of example 1, including or excludingoptional features. In this example, growing monolithically comprisesgrowing a first plurality of nanowires to a first diameter for the firstcolor nanowire LED and a second plurality of nanowires to a seconddiameter for the second color nanowire LED, the second diameter largerthan the first diameter.

Example 3 includes the method of any one of examples 1 to 2, includingor excluding optional features. In this example, the method includesgrowing monolithically a second color nanowire LED and a third colornanowire LED on another wafer to give a second micro-structure having asecond color micro-LED and a third color micro-LED, and transferring thesecond micro-structure from the another wafer to the backplane for thepixel. Optionally, growing monolithically comprises growing indiumgallium nitride (InGaN), and wherein performing transfers to thebackplane for the pixel comprises performing four separate transferscomprising the transferring of the first micro-structure from the waferto the backplane, the transferring of the second micro-structure fromthe another wafer to the backplane, transferring a blue micro-LEDcomprising a blue nanowire LED to the backplane from a third wafer, andtransferring a red micro-LED comprising a red nanowire LED to thebackplane from a fourth wafer. Optionally, no more transfers than thefour separate transfers are performed for the pixel. Optionally, thefirst color is blue, the second color is green, and the third color isred.

Example 4 includes the method of any one of examples 1 to 3, includingor excluding optional features. In this example, the method includesforming the micro-LED display panel with the backplane, wherein thefirst color is blue and the second color is green.

Example 5 includes the method of any one of examples 1 to 4, includingor excluding optional features. In this example, the first color isgreen and the second color is red.

Example 6 includes the method of any one of examples 1 to 5, includingor excluding optional features. In this example, the first color isgreen and the second color is yellow.

Example 7 includes the method of any one of examples 1 to 6, includingor excluding optional features. In this example, the first color isyellow and the second color is red.

Example 8 includes the method of any one of examples 1 to 7, includingor excluding optional features. In this example, the method includesgrowing a first color nanowire LED comprising a first color micro-LED onanother wafer and transferring the first color micro-LED from theanother wafer to the backplane for the pixel.

Example 9 is a method of forming a micro-light emitting diode (LED)display panel having pixels. The method includes growing monolithicallya blue (B) nanowire LED and a green (G) nanowire LED to give a BGmicro-structure having a B micro-LED and a G micro-LED; growingmonolithically a green (G) nanowire LED and a red (R) nanowire LED togive a GR micro-structure having a G micro-LED and a R micro-LED;growing a blue (B) nanowire LED comprising a B micro-LED; growing a red(R) nanowire LED comprising a R micro-LED; and performing four separatetransfers to a backplane substrate for a pixel of the micro-LED displaypanel, comprising separate respective transfers of the B micro-LED, theBG micro-structure, the GR micro-structure, and the R micro-LED.

Example 10 includes the method of example 9, including or excludingoptional features. In this example, no more transfers than the fourseparate transfers are performed for the pixel.

Example 11 includes the method of any one of examples 9 to 10, includingor excluding optional features. In this example, the method includesforming the micro-LED display panel with the backplane substrate.

Example 12 includes the method of any one of examples 9 to 11, includingor excluding optional features. In this example, the method includesinstalling the micro-LED display panel in a display of an electronicdevice.

Example 13 is a micro-light emitting diode (LED) display panel. Themicro-light emitting diode (LED) display panel includes a monolithicallygrown micro-structure comprising: a first color micro-LED comprising afirst plurality of nanowires; and a second color micro-LED comprising asecond plurality of nanowires, the second color different than the firstcolor.

Example 14 includes the micro-light emitting diode (LED) display panelof example 13, including or excluding optional features. In thisexample, the micro-light emitting diode (LED) display panel includes amonolithically-grown second micro-structure comprising a second colormicro-LED comprising a third plurality of nanowires and a third colormicro-LED comprising a fourth plurality of nanowires. Optionally, thefirst color is blue, the second color is green, and the third color isred.

Example 15 includes the micro-light emitting diode (LED) display panelof any one of examples 13 to 14, including or excluding optionalfeatures. In this example, the first plurality of nanowires comprisesnanowires with a first diameter, wherein the second plurality ofnanowires comprises nanowires having a second diameter larger than thefirst diameter, and wherein the first color is blue and the second coloris green.

Example 16 includes the micro-light emitting diode (LED) display panelof any one of examples 13 to 15, including or excluding optionalfeatures. In this example, the first color is green and the second coloris red.

Example 17 includes the micro-light emitting diode (LED) display panelof any one of examples 13 to 16, including or excluding optionalfeatures. In this example, the first color is green and the second coloris yellow.

Example 18 includes the micro-light emitting diode (LED) display panelof any one of examples 13 to 17, including or excluding optionalfeatures. In this example, the first color is yellow and the secondcolor is red.

Example 19 is an electronic device. The electronic device includes amicro-light emitting diode (LED) display panel comprising a pixel,wherein the pixel comprises a monolithically grown blue-green (BG) LEDmicro-structure comprising a blue (B) nanowire LED and a green (G)nanowire LED.

Example 20 includes the electronic device of example 19, including orexcluding optional features. In this example, the pixel comprises amonolithically grown green-red (GR) LED micro-structure comprising agreen (G) nanowire LED and a red (R) nanowire LED. Optionally, the pixelcomprises a second blue (B) nanowire LED and a second red (R) nanowireLED.

Example 21 is a method of forming a micro-light emitting diode (LED)display panel. The method includes growing monolithically a first colornanowire LED and a second color nanowire LED on a wafer to give amicro-structure having a first color micro-LED and a second colormicro-LED, the second color different than the first color, whereingrowing monolithically comprises growing a first plurality of nanowiresto a first diameter for the first color nanowire LED and a secondplurality of nanowires to a second diameter for the second colornanowire LED, the second diameter larger than the first diameter; andtransferring the micro-structure from the wafer to a backplane for apixel of the micro-LED display, wherein the micro-structure to provideemission colors of the first color and the second color.

Example 22 includes the method of example 21, including or excludingoptional features. In this example, the method includes growingmonolithically a second color nanowire LED and a third color nanowireLED on another wafer to give a second micro-structure having a secondcolor micro-LED and a third color micro-LED, and transferring the secondmicro-structure from the another wafer to the backplane for the pixel.Optionally, growing monolithically comprises growing indium galliumnitride (InGaN), and wherein performing transfers to the backplane forthe pixel comprises performing four separate transfers comprising thetransferring of the first micro-structure from the wafer to thebackplane, the transferring of the second micro-structure from theanother wafer to the backplane, transferring a blue micro-LED comprisinga blue nanowire LED to the backplane from a third wafer, andtransferring a red micro-LED comprising a red nanowire LED to thebackplane from a fourth wafer. Optionally, the first color is blue, thesecond color is green, and the third color is red.

Example 23 includes the method of any one of examples 21 to 22,including or excluding optional features. In this example, the firstcolor is blue and the second color is green, or wherein the first coloris green and the second color is red, or wherein the first color isgreen and the second color is yellow, or wherein the first color isyellow and the second color is red.

Example 24 includes the method of any one of examples 21 to 23,including or excluding optional features. In this example, the methodincludes growing a first color nanowire LED comprising a first colormicro-LED on another wafer and transferring the first color micro-LEDfrom the another wafer to the backplane for the pixel; and forming themicro-LED display panel with the backplane,

Example 25 is a method of forming a micro-light emitting diode (LED)display panel having pixels. The method includes growing monolithicallya blue (B) nanowire LED and a green (G) nanowire LED to give a BGmicro-structure having a B micro-LED and a G micro-LED; growingmonolithically a green (G) nanowire LED and a red (R) nanowire LED togive a GR micro-structure having a G micro-LED and a R micro-LED;growing a blue (B) nanowire LED comprising a B micro-LED; growing a red(R) nanowire LED comprising a R micro-LED; and performing four separatetransfers to a backplane substrate for a pixel of the micro-LED displaypanel, comprising separate respective transfers of the B micro-LED, theBG micro-structure, the GR micro-structure, and the R micro-LED.

Example 26 includes the method of example 25, including or excludingoptional features. In this example, no more transfers than the fourseparate transfers are performed for the pixel.

Example 27 includes the method of any one of examples 25 to 26,including or excluding optional features. In this example, the methodincludes forming the micro-LED display panel with the backplanesubstrate.

Example 28 includes the method of any one of examples 25 to 27,including or excluding optional features. In this example, the methodincludes installing the micro-LED display panel in a display of anelectronic device.

Example 29 is a micro-light emitting diode (LED) display panel. Themicro-light emitting diode (LED) display panel includes a monolithicallygrown micro-structure comprising: a first color micro-LED comprising afirst plurality of nanowires; and a second color micro-LED comprising asecond plurality of nanowires, the second color different than the firstcolor, wherein the first plurality of nanowires comprises nanowires witha first diameter, wherein the second plurality of nanowires comprisesnanowires having a second diameter larger than the first diameter.

Example 30 includes the micro-light emitting diode (LED) display panelof example 29, including or excluding optional features. In thisexample, the micro-light emitting diode (LED) display panel includes amonolithically-grown second micro-structure comprising a second colormicro-LED comprising a third plurality of nanowires and a third colormicro-LED comprising a fourth plurality of nanowires. Optionally, thefirst color is blue, the second color is green, and the third color isred.

Example 31 includes the micro-light emitting diode (LED) display panelof any one of examples 29 to 30, including or excluding optionalfeatures. In this example, the first color is blue and the second coloris green, or wherein the first color is green and the second color isred, or wherein the first color is green and the second color is yellow,or wherein the first color is yellow and the second color is red.

Example 32 includes the micro-light emitting diode (LED) display panelof any one of examples 29 to 31, including or excluding optionalfeatures. In this example, the micro-LED display panel is installed inan electronic device.

Example 33 is a system for forming a micro-light emitting diode (LED)display panel. The system includes means for growing monolithically afirst color nanowire LED and a second color nanowire LED on a wafer togive a micro-structure having a first color micro-LED and a second colormicro-LED, the second color different than the first color; and meansfor transferring the micro-structure from the wafer to a backplane for apixel of the micro-LED display, wherein the micro-structure to provideemission colors of the first color and the second color.

Example 34 includes the system of example 33, including or excludingoptional features. In this example, growing monolithically comprisesgrowing a first plurality of nanowires to a first diameter for the firstcolor nanowire LED and a second plurality of nanowires to a seconddiameter for the second color nanowire LED, the second diameter largerthan the first diameter.

Example 35 includes the system of any one of examples 33 to 34,including or excluding optional features. In this example, the systemincludes means for growing monolithically a second color nanowire LEDand a third color nanowire LED on another wafer to give a secondmicro-structure having a second color micro-LED and a third colormicro-LED, and means for transferring the second micro-structure fromthe another wafer to the backplane for the pixel. Optionally, growingmonolithically comprises growing indium gallium nitride (InGaN), andwherein means for performing transfers to the backplane for the pixelcomprises means for performing four separate transfers comprising thetransferring of the first micro-structure from the wafer to thebackplane, the transferring of the second micro-structure from theanother wafer to the backplane, transferring a blue micro-LED comprisinga blue nanowire LED to the backplane from a third wafer, andtransferring a red micro-LED comprising a red nanowire LED to thebackplane from a fourth wafer. Optionally, no more transfers than thefour separate transfers are performed for the pixel. Optionally, thefirst color is blue, the second color is green, and the third color isred.

Example 36 includes the system of any one of examples 33 to 35,including or excluding optional features. In this example, the systemincludes means for forming the micro-LED display panel with thebackplane, wherein the first color is blue and the second color isgreen.

Example 37 includes the system of any one of examples 33 to 36,including or excluding optional features. In this example, the firstcolor is green and the second color is red.

Example 38 includes the system of any one of examples 33 to 37,including or excluding optional features. In this example, the firstcolor is green and the second color is yellow.

Example 39 includes the system of any one of examples 33 to 38,including or excluding optional features. In this example, the firstcolor is yellow and the second color is red.

Example 40 includes the system of any one of examples 33 to 39,including or excluding optional features. In this example, the systemincludes means for growing a first color nanowire LED comprising a firstcolor micro-LED on another wafer and means for transferring the firstcolor micro-LED from the another wafer to the backplane for the pixel.

Example 41 is a system for forming a micro-light emitting diode (LED)display panel having pixels. The system includes means for growingmonolithically a blue (B) nanowire LED and a green (G) nanowire LED togive a BG micro-structure having a B micro-LED and a G micro-LED; meansfor growing monolithically a green (G) nanowire LED and a red (R)nanowire LED to give a GR micro-structure having a G micro-LED and a Rmicro-LED; means for growing a blue (B) nanowire LED comprising a Bmicro-LED; means for growing a red (R) nanowire LED comprising a Rmicro-LED; and means for performing four separate transfers to abackplane substrate for a pixel of the micro-LED display panel,comprising separate respective transfers of the B micro-LED, the BGmicro-structure, the GR micro-structure, and the R micro-LED.

Example 42 includes the system of example 41, including or excludingoptional features. In this example, no more transfers than the fourseparate transfers are performed for the pixel.

Example 43 includes the system of any one of examples 41 to 42,including or excluding optional features. In this example, the systemincludes means for forming the micro-LED display panel with thebackplane substrate.

Example 44 includes the system of any one of examples 41 to 43,including or excluding optional features. In this example, the systemincludes means for installing the micro-LED display panel in a displayof an electronic device.

Example 45 is a method of forming a micro-light emitting diode (LED)display panel. The method includes growing monolithically a blue (B) andgreen (G) nanowire LED on a wafer; and transferring the BG nanowire LEDfrom the wafer to a backplane for a pixel of the micro-LED displaypanel, wherein the BG nanowire LED to provide emission colors of blue(B) and green (G).

Example 46 includes the method of example 45, including or excludingoptional features. In this example, growing monolithically comprisesgrowing a first diameter of a first nanowire for the BG nanowire LED andgrowing a second diameter of a second nanowire for the BG nanowire LED,the second diameter larger than the first diameter.

Example 47 includes the method of any one of examples 45 to 46,including or excluding optional features. In this example, growingmonolithically comprises growing indium gallium nitride (InGaN).

Example 48 includes the method of any one of examples 45 to 47,including or excluding optional features. In this example, the methodincludes growing monolithically a green (G) and red (R) nanowire LED,and transferring the GR nanowire LED to the backplane for the pixel.

Example 49 includes the method of any one of examples 45 to 48,including or excluding optional features. In this example, the methodincludes growing a red (R) nanowire LED and transferring the R nanowireLED to the backplane for the pixel.

Example 50 includes the method of any one of examples 45 to 49,including or excluding optional features. In this example, the methodincludes growing a blue (B) nanowire LED and transferring the B nanowireLED to the backplane for the pixel.

Example 51 includes the method of any one of examples 45 to 50,including or excluding optional features. In this example, the methodincludes growing monolithically a green (G) and red (R) nanowire LED,and transferring the GR nanowire LED to the backplane for the pixel; andperforming four separate transfers to the backplane for the pixel,comprising the transferring of the BG nanowire LED, transferring of theGR nanowire LED to the backplane, transferring of a blue (B) nanowireLED to the backplane, and transferring a red nanowire LED to thebackplane. Optionally, the method includes growing the B nanowire LEDand growing the R nanowire LED. Optionally, no more transfers than thefour separate transfers are performed for the pixel.

Example 52 includes the method of any one of examples 45 to 51,including or excluding optional features. In this example, the methodincludes growing monolithically a green (G) and yellow (Y) nanowire LED,and transferring the GY nanowire LED to the backplane.

Example 53 includes the method of any one of examples 45 to 52,including or excluding optional features. In this example, the methodincludes growing monolithically a yellow (Y) and red (R) nanowire LED,and transferring the YR nanowire LED to the backplane.

Example 54 includes the method of any one of examples 45 to 53,including or excluding optional features. In this example, the methodincludes forming the micro-LED display panel with the backplane.

Example 55 includes the method of any one of examples 45 to 54,including or excluding optional features. In this example, the methodincludes installing the micro-LED display panel in a display.

It is to be understood that specifics in the aforementioned examples maybe used anywhere in one or more embodiments. For instance, all optionalfeatures of the computing device described above may also be implementedwith respect to either of the methods described herein or acomputer-readable medium. Furthermore, although flow diagrams or statediagrams may have been used herein to describe embodiments, the presenttechniques are not limited to those diagrams or to correspondingdescriptions herein. For example, flow need not move through eachillustrated box or state or in exactly the same order as illustrated anddescribed herein.

The present techniques are not restricted to the particular detailslisted herein. Indeed, those skilled in the art having the benefit ofthis disclosure will appreciate that many other variations from theforegoing description and drawings may be made within the scope of thepresent techniques. Accordingly, it is the following claims includingany amendments thereto that define the scope of the present techniques.

What is claimed is:
 1. A micro-light emitting diode (LED) display panelcomprising: a monolithically grown micro-structure comprising: a firstcolor micro-LED comprising a first plurality of nanowires; and a secondcolor micro-LED comprising a second plurality of nanowires, the secondcolor different than the first color.
 2. The micro-LED display panel ofclaim 1, comprising a monolithically-grown second micro-structurecomprising a second color micro-LED comprising a third plurality ofnanowires and a third color micro-LED comprising a fourth plurality ofnanowires.
 3. The micro-LED display panel of claim 1, wherein the firstcolor is blue, the second color is green, and the third color is red. 4.The micro-LED display panel of claim 1, wherein the first plurality ofnanowires comprises nanowires with a first diameter, and wherein thesecond plurality of nanowires comprises nanowires having a seconddiameter larger than the first diameter.
 5. The micro-LED display panelof claim 4, wherein the first color is blue and the second color isgreen.
 6. The micro-LED display panel of claim 1, wherein the firstcolor is blue and the second color is green.
 7. The micro-LED displaypanel of claim 1, wherein the first color is green and the second coloris red.
 8. The micro-LED display panel of claim 1, wherein the firstcolor is green and the second color is yellow.
 9. The micro-LED displaypanel of claim 1, wherein the first color is yellow and the second coloris red.
 10. The micro-LED display panel of claim 1, wherein themonolithically grown micro-structure emits colors of the first color andthe second color.
 11. The micro-LED display panel of claim 1, comprisinga backplane including the monolithically grown micro-structure.
 12. Themicro-LED display panel of claim 11, wherein the backplane is a glassbackplane.
 13. The micro-LED display panel of claim 1, comprising athird color micro-LED comprising a third plurality of nanowires, thethird color different than the first color, and the third colordifferent than the second color.
 14. The micro-LED display panel ofclaim 1, comprising: a monolithically grown second micro-structurecomprising: a second color micro-LED comprising a third plurality ofnanowires; and a third color micro-LED comprising a fourth plurality ofnanowires, the third color different than the second color.
 15. Themicro-LED display panel of claim 1, wherein the first color micro-LEDand the second color micro-LED are integrated as a single unit.
 16. Themicro-LED display panel of claim 1, wherein the first color micro-LEDand the second color micro-LED have different indium compositions. 17.An electronic device comprising a micro-light emitting diode (LED)display panel comprising a pixel, wherein the pixel comprises amonolithically grown blue-green (BG) LED micro-structure comprising ablue (B) nanowire LED and a green (G) nanowire LED.
 18. The electronicdevice of claim 17, wherein the pixel comprises a monolithically growngreen-red (GR) LED micro-structure comprising a green (G) nanowire LEDand a red (R) nanowire LED.
 19. The electronic device of claim 18,wherein the pixel comprises a second blue (B) nanowire LED and a secondred (R) nanowire LED.
 20. An electronic device comprising a micro-lightemitting diode (LED) display panel comprising: a monolithically grownmicro-structure comprising: a first color micro-LED comprising a firstplurality of nanowires; and a second color micro-LED comprising a secondplurality of nanowires, the second color different than the first color.21. The electronic device of claim 20, the micro-light emitting displaypanel comprising a monolithically-grown second micro-structurecomprising a second color micro-LED comprising a third plurality ofnanowires and a third color micro-LED comprising a fourth plurality ofnanowires.
 22. The electronic device of claim 20, wherein the firstplurality of nanowires comprises nanowires with a first diameter, andwherein the second plurality of nanowires comprises nanowires having asecond diameter larger than the first diameter.
 23. A micro-lightemitting diode (LED) display panel comprising: a monolithically grownmicro-structure comprising: a first color nanowire LED; and a secondcolor nanowire LED, the second color different than the first color. 24.The micro-LED display panel of claim 23, comprising a third colornanowire LED, the third color different than the first color, and thethird color different than the second color.
 25. The micro-LED displaypanel of claim 23, comprising: a second monolithically grownmicro-structure comprising: a second color nanowire LED; and a thirdcolor nanowire LED, the second color different than the first color.